Recognizing and Avoiding Faulty Reasoning

• Attacking the person. Arguing against other people’s positions or attacking their arguments is perfectly acceptable. Going after their personalities, however, is not OK. Any argument that resorts to personal attack (“Why should we believe a cheater?”) is unworthy of consideration.
• Begging. “Please, officer, don’t give me a ticket! If you do, I’ll lose my license, and I have five little children to feed, and I won’t be able to feed them if I can’t drive my truck.” None of the driver’s statements offer any evidence, in any legal sense, as to why she shouldn’t be given a ticket. Pleading might work if the officer is feeling generous, but an appeal to facts and reason would be more effective: “I fed the meter, but it didn’t register the coins. Since the machine is broken, I’m sure you’ll agree that I don’t deserve a ticket.”
• Appealing to false authority. Citing authorities, such as experts in a field or the opinions of qualified researchers, can offer valuable support for an argument. However, a claim based on the authority of someone whose expertise is questionable relies on the appearance of authority rather than on real evidence. We see examples of false authority all the time in advertising: Sports stars who are not doctors, dieticians, or nutritionists urge us to eat a certain brand of food; famous actors and singers who are not dermatologists extol the medical benefits of a costly remedy for acne.
• Jumping on a bandwagon. Sometimes we are more likely to believe something that many others also believe. Even the most widely accepted truths can turn out to be wrong, however. At one time, nearly everyone believed that the world was flat, until someone came up with evidence to the contrary.
• Assuming that something is true because it hasn’t been proven false. If you go to a bookstore or look online, you’ll find dozens of books detailing close encounters with flying saucers and extraterrestrial beings. These books describe the people who had such encounters as beyond reproach in their integrity and sanity. Because critics could not disprove the claims of the witnesses, the events are said to have actually occurred. Even in science, few things are ever proved completely false, but evidence can be discredited.
• Falling victim to false cause. Frequently, we make the assumption that just because one event followed another, the first event must have caused the second. This reasoning is the basis for many superstitions. The ancient Chinese once believed that they could make the sun reappear after an eclipse by striking a large gong, because they knew that on a previous occasion the sun had reappeared after a large gong had been struck. Most effects, however, are usually the result of a complex web of causes. Don’t be satisfied with easy before-and-after claims; they are rarely correct.
• Making hasty generalizations. If someone selected a green marble from a barrel containing a hundred marbles, you wouldn’t assume that the next marble drawn from the barrel would also be green. After all, you know nothing about the colors of the ninety-nine marbles still in the barrel. However, if you were given fifty draws from the barrel, and each draw produced a green marble after the barrel had been shaken thoroughly, you would be more willing to conclude that the next marble drawn would be green, too. Reaching a conclusion based on the opinion of one source is like assuming that all the marbles in the barrel are green after pulling out only one marble.
• Slippery slope. “If we allow tuition to increase, the next thing we know, it will be $20,000 per term.” Such an argument is an example of “slippery slope” thinking. Fallacies like these can slip into even the most careful reasoning. One false claim can derail an entire argument, so be on the lookout for weak logic in what you read and write. Never forget that accurate reasoning is a key factor in succeeding in college and in life.